Bruce, sorry for the trouble you're having... as to Professional Musicians Should Be Thrilled To Be Paid At All, (since they're doing what they love) - well, last minute cues and untidy parts books are not all that lovable. It's very stressful. Happy and fun is more likely to engender the desire to work for free... stressful wants compensation.
Plus, this is what they do in order to pay their mortgages and buy new Nikes for their kids... some of them can't bear the work any longer, but can't find anything else that pays as well. A couple of my old pals from Juilliard finally quit their tenured jobs in the New York City Opera pit and the Phantom of the Opera pit, and moved to Ventura to work in a scuba store...
Up in Seattle, we had wonderful musicians who called in sick at Seattle Symphony, in order to play our gigs - for a third less than SSO was paying them -- because they felt unappreciated and abused at SSO, and felt loved and cherished with us... but we called Union breaks and provided whatever we could to please them. There was NO drama, EVER, and if we wanted them to stay an extra fifteen (almost NEVER), we offered compensation, which most of them declined to accept. We were considered a plum gig, and did everything we could to keep it that way...